1. Field of the Invention
The present invention generally relates to an image processing apparatus, an image processing method, and a computer-readable recording medium storing an image processing program in which a preview image and/or a thumbnail image of a document image is displayed by forming the preview image and/or the thumbnail image of the document image.
2. Description of the Related Art
Recently, in image processing apparatuses, in order to reduce the amount of paper to be used in printing, a preview image and/or a thumbnail image of a document image is formed, and in order to perform aggregation printing of plural images, an image reducing process is performed.
For example, in Patent Document 1, a predetermined range of a document to be read is displayed on a preview screen, and editing processes such as an image moving process, an image enlarging process, an image reducing process, and an image density changing process are performed on the preview screen. In Patent Document 2, when finishing items of an output image are determined, finishing conditions of the items are displayed as a preview image.
When a reduced preview image of an image is displayed on a preview screen, and plural images are displayed on the preview screen as a list of thumbnail images by reducing the plural images, reduced images are formed. Generally, when an image is reduced, the sum of the number of pixels of a target region of an input image to be reduced is obtained, the sum of the number of the pixels is divided by the number of pixels of the reduction region, and pixel values of the image to be reduced are obtained. However, the workload of the CPU (central processing unit) is great and a large amount of processing time is required.
That is, in the conventional preview image display, the workload of the CPU has not been studied.    [Patent Document 1] Japanese Unexamined Patent Publication No. 2006-126401    [Patent Document 2] Japanese Unexamined Patent Publication No. 2006-041947
In the conventional technologies of Patent Documents 1 and 2, when a preview image and/or a thumbnail image is to be efficiently displayed, the usability must be studied. That is, the preview image and/or the thumbnail image is a reduced image of an original image and when the preview image and/or the thumbnail image is displayed on image processing apparatuses having different resolutions, plural types of the preview image and/or the thumbnail must be prepared for the plural image processing apparatuses. However, the workload of the CPU in the image processing apparatuses such as a multifunctional apparatus having an image processing function and a copying apparatus becomes great, and the processing time becomes long. Consequently, the usability of displaying the preview image and/or the thumbnail image is lowered. In Patent Documents 1 and 2, only preview image and/or thumbnail image forming and storing processes are disclosed, and the workload of the CPU has not been studied. That is, the usability, for example, shortening the processing time, has not been described.